Apple has an application pending that would probably go into iPhones. The idea is that you have the camera or fingerprint scanner or other electronic component behind a window that can be turned transparent or opaque (probably an LCD layer). The window could also be behind the LCD screen itself, so the display would be normal, but then could selectively show the camera through the display when needed. The publication is 2012/0258773. I've seen some articles talking about this application, so I feel it may be one that Apple is paying attention to. It seems cool, but is it really patent-worthy?

A component disposed behind the window, wherein the component comprises an image capture device, a strobe flash, a biometric
sensor, a light sensor, a proximity sensor, or a solar panel, or a
combination thereof;

Data processing circuitry configured to determine when an event requesting that the component be exposed occurs; and

A window controller configured to cause the window to become transparent to expose the component upon the occurrence of the event
requesting that the component be exposed.

None of the components of the described application are new. Detecting an event is not new: computers have handled events since the dawn of computing. Generating a response to an event is not new, for the same reason. Use of a liquid crystal for electronically-activated opacity is not new. The basis for this patent is the idea that responding to a particular kind of event (an event that requires some sensor to become exposed to light) triggers the activation of a particular kind of controller (some circuit that triggers the opacity of a panel) constitutes a brand new invention.
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KazJul 19 '14 at 0:32

At the broadest level, the pattern here is that we have a device D, and two peripherals P1 and P2. These are related together: an event which indicates that P2 must be activated for use requires P1 to be activated also, and deactivated when P2 is no longer in use. Here P2 is the window, and P1 is the sensor or whatever. In prior art there are other P1's and P2's. For instance, sometimes a P2 device is powered down, and P1 is chip, itself a peripheral, which, when activated, supplies power to P2. Power, visibility; it's all the same: a secondary factor to enable the use of that peripheral.
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KazJul 19 '14 at 0:34

Another example: before we can read a magnetic tape (via a tape head sensor: device P2), we must actuate the motor to move the tape (related peripheral P1).
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KazJul 19 '14 at 0:36